Motor bogging down on full throttle

[THE BESTEVER]

First time on here but having some issues with my johnson 1978 115hp bogging down at full throttle runs ok at 3/4 to half throttle I'm going about 28mph but would like to get more out of the motor. I run sea foam every fill up. compression is 125 120 120 110 new plugs gapped at .30

 

[ondarvr]

Clean the carbs, and don't run it that way, you can destroy the motor quickly. Could be a bad fuel pump, air leak, plugged carbs, or a few other not good things.

 

[interalian]

I'd say don't run Seafoam, and try pumping the primer bulb when it's 'bogging' - if it picks up you're starving for fuel supply to the carbs. It's an easy first test that would prove fuel pump problems or air leaks in the fuel lines.

 

[THE BESTEVER]

Thanks I'm leaning toward just replacing fuel pump and see what I can get. Seen one on eBay $40

 

[ondarvr]

Unless you like spending money, try pumping the squeeze bulb first, this will tell you immediately if the fuel pump is a possible cause.

 

[THE BESTEVER]

Changed fuel pump going to test it in a few days I will be sure to post my results.

 

[jakedaawg]

Personally, I tgink you should further investigate the low comp cylinder. Pop off head or exhast cover, may find bad ring and scoring, better to fix sooner than later.